The lung is the route of entrance and exist of the commonly employed halogenated inhalation anesthetics. Preliminary evidence from the authors' laboratory indicates that these drugs are biotransformed to a considerable extent by the lung; an effect that has not been previously investigated. There is strong support that biotransformation of these anesthetics can, under certain circumstances, produce harmful products and/or reactive intermediates. This is work which has primarily been done in the liver but not in the lung. This phenomenon of lung biotransformation may be linked to the common occurrence of post-anesthetic pulmonary cellular dysfunction seen in man. It is the intent of proposed study to ascertain the qualitative and quantitative aspects of halogenated anesthetic biotransformation under a variety of environmental influences and couple this with studies of lung cell dysfunction using the rabbit lung as a model. Specifically, the relationship of biotransformation of the anesthetic compounds with pulmonary lipoperoxidation, loss of antioxidant activity, and alterations of surfactant activity are proposed. The importance of this area of investigation is that it may cast light on a heretofore unrecognized area of anesthetic activity, and may give insight into the problem of post-anesthetic pulmonary dysfunction.